Manufacturing method of highly heat-resistant sound absorbing and insulating materials

Abstract

The present invention relates to a method for manufacturing a substantially improved heat-resistant sound absorbing and insulating material. method includes: beating and mixing a fiber material comprising a heat-resistant fiber; forming a web from the beaten and mixed fiber material; stacking the formed web; forming a nonwoven fabric by needle punching as moving a needle up and down through the stacked web; forming a binder-impregnated nonwoven fabric by immersing the nonwoven fabric in a binder solution; and removing a solvent from the binder-impregnated nonwoven fabric. The substantially improved heat-resistant sound absorbing and insulating material manufactured by the method according to the present invention may be installed on a location closest to the noise source of an engine or an exhaust system to reduce radiated noise from the engine or the exhaust system, thereby improving quietness inside a vehicle, and may be applied to a location adjacent to a metal part which is at a temperature of 200° C. or greater to exert heat-insulating function, thereby protecting nearby plastic and rubber parts.

What is claimed is: 
     
         1 . A method for manufacturing a heat-resistant sound absorbing and insulating material, comprising:
 beating and mixing a fiber material comprising a heat-resistant fiber;   forming a web from the beaten and mixed fiber material;   stacking the formed web;   forming a nonwoven fabric by needle punching as moving a needle up and down through the stacked web;   forming a binder-impregnated nonwoven fabric by immersing the nonwoven fabric in a binder solution; and   removing a solvent from the binder-impregnated nonwoven fabric.   
     
     
         2 . The method of  claim 1 , further comprising:
 shaping and molding the nonwoven fabric from which the solvent is removed into a desired shape.   
     
     
         3 . The method of  claim 1 , wherein the beating and mixing step comprises beating, mixing or beating and mixing a fiber material having a limiting oxygen index (LOI) of about 25% or greater and a heat resistance temperature of about 200° C. or greater. 
     
     
         4 . The method of  claim 1 , wherein the beating and mixing step comprises beating a fiber material having about 1-10 crimps/cm and having a diameter of about 1-33 μm and a length of about 20-100 mm or mixing one or more fiber material having about 1-10 crimps/cm and having a diameter of about 1-33 μm and a length of about 20-100 mm. 
     
     
         5 . The method of  claim 3 , wherein the fiber material comprises one or more selected from the group consisting of an aramid fiber, a polyphenylene sulfide (PPS) fiber, an oxidized polyacrylonitrile (oxi-PAN) fiber, a polyimide (PI) fiber, a polybenzimidazole (PBI) fiber, a polybenzoxazole (PBO) fiber, a polytetrafluoroethylene (PTFE) fiber, a polyketone (PK) fiber, a metallic fiber, a carbon fiber, a glass fiber, a basalt fiber, a silica fiber and a ceramic fiber. 
     
     
         6 . The method of  claim 5 , wherein the fiber material comprises one or more selected from the group consisting of a meta-aramid (m-aramid) fiber and a para-aramid (p-aramid) fiber. 
     
     
         7 . The method of  claim 1 , wherein the web forming step is performed by carding method. 
     
     
         8 . The method of  claim 1 , wherein the web stacking step is performed at a rate of 10 m/min or lower using a horizontal wrapper. 
     
     
         9 . The method of  claim 1 , wherein the needle punching step is performed by one or more selected from the group consisting of single down needle punching, single up needle punching, double down needle punching and double up needle punching. 
     
     
         10 . The method of  claim 9 , wherein the needle punching step comprises forming a nonwoven fabric with a needle stroke of about 30-350 times/m 2 . 
     
     
         11 . The method of  claim 1 , wherein the nonwoven fabric formed in the needle punching step has a single layer thickness of about 3-20 mm and a density of about 100-2000 g/m 2 . 
     
     
         12 . The method of  claim 1 , wherein the binder impregnating step comprises immersing the nonwoven fabric formed in the needle punching step in a binder solution wherein a thermosetting binder resin having a heat resistance temperature of about 200° C. or greater is dispersed in an organic solvent at a concentration of about 5-70 wt %. 
     
     
         13 . The method of  claim 12 , wherein the binder impregnating step further comprises compressing the binder-impregnated nonwoven fabric at a pressure of about 1-20 kgf/cm 2  to form a binder-impregnated nonwoven fabric having a density of about 1,000-3,000 g/m 2 . 
     
     
         14 . The method of  claim 12 , wherein the binder impregnating step comprises impregnating an amount of about 20-80 parts by weight of a thermosetting binder resin in an amount of about 20-80 parts by weight of the nonwoven fabric. 
     
     
         15 . The method of  claim 12 , wherein the binder solution comprises an amount of about 5-70 wt % of a binder resin, an amount of about 0.1-10 wt % of a curing agent, an amount of about 0.01-5 wt % of a catalyst, an amount of about 1-40 wt % of an additive and a solvent as the balance, based on the total weight of the binder solution. 
     
     
         16 . The method of  claim 15 , wherein the binder solution comprises an amount of about 1-30 wt % of a binder resin, an amount of about 0.1-10 wt % of a curing agent, an amount of about 0.01-5 wt % of a catalyst, 1-30 wt % of a flame retardant and 40-95 wt % of a solvent, based on the total weight of the binder solution. 
     
     
         17 . The method of  claim 12 , wherein the thermosetting binder resin is an epoxy resin. 
     
     
         18 . The method of  claim 17 , wherein the epoxy resin is one or more selected from bisphenol A diglycidyl ether, bisphenol B diglycidyl ether, bisphenol AD diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, polyoxypropylene diglycidyl ether, bisphenol A diglycidyl ether polymer, phosphazene diglycidyl ether, bisphenol A novolac epoxy, phenol novolac epoxy resin, and o-cresol novolac epoxy resin. 
     
     
         19 . The method of  claim 1 , wherein the solvent recovering step comprises evaporating the organic solvent by drying in a drying oven at a temperature of about 70-200° C. for about 1-10 minutes. 
     
     
         20 . The method of  claim 19 , wherein the nonwoven fabric that has passed through the solvent recovering step comprises an amount of about 1-300 parts by weight of a binder based on 100 parts by weight of the nonwoven fabric. 
     
     
         21 . The method of  claim 19 , wherein the organic solvent is one or more selected from the group consisting of methyl ethyl ketone (MEK) and dimethyl carbonate (DMC). 
     
     
         22 . The method of  claim 2 , wherein the molding step is performed at about 150-300° C. 
     
     
         23 . The method of  claim 1 , which comprises:
 beating and mixing a fiber material having a limiting oxygen index (LOI) of about 25% or greater and a heat resistance temperature of about 200° C. or greater;   forming the fiber material beaten and mixed in the beating and mixing step into a continuous web in the form of a thin sheet;   forming a stacked web by overlapping and stacking the web formed in the web forming step with each other;   forming a nonwoven fabric by binding the stacked web formed in the web stacking step with each other by moving a needle up and down through the stacked web;   forming a binder-impregnated nonwoven fabric by immersing the nonwoven fabric formed in the needle punching step in a binder solution wherein a thermosetting binder resin having a heat resistance temperature of about 200° C. or greater is dispersed in an organic solvent; and   forming a thermosetting felt for use as a sound absorbing and insulating material by removing the solvent from the binder-impregnated nonwoven fabric formed in the binder impregnating step such that only the thermosetting binder resin remains.   
     
     
         24 . The method of  claim 23 , which further comprises, after removing the solvent, shaping the nonwoven fabric into a desired shape by molding at a temperature of about 150-300° C. 
     
     
         25 . The method of  claim 1 , wherein the sound absorbing and insulating material has the binder distributed uniformly on the entire fiber yarn of the nonwoven fabric and has smaller-sized vent holes or microcavities formed as compared to before the impregnation of the binder. 
     
     
         26 . A method for reducing noise of a noise generating device, comprising:
 i) identifying the three-dimensional shape of a noise generating device;   ii) manufacturing and molding a sound absorbing and insulating material by the method of  claim 1  so as to correspond partially or entirely to the three-dimensional shape of the device; and   iii) bringing the sound absorbing and insulating material adjacent to the noise generating device.   
     
     
         27 . The method of  claim 26 , wherein the device is a motor, an engine or an exhaust system. 
     
     
         28 . The method of  claim 26 , wherein said bringing the sound absorbing and insulating material adjacent to the noise generating device comprises closely attaching the sound absorbing and insulating material to the noise generating device, installing the sound absorbing and insulating material to be spaced apart from the noise generating device or molding the sound absorbing and insulating material as a part of the noise generating device. 
     
     
         29 . A vehicle part that comprises a heat-resistant sound absorbing and insulating material manufactured by a method of  claim 1 .